The present invention relates to a carrying apparatus for conveying a paper sheet and an image forming apparatus which are comprised, for example, in an electrophotographic copying machine.
In many electrophotographic copying machines, images can be formed on both surfaces of a paper sheet. To form images on both surfaces in this kind of copying machine, a paper sheet is supplied from a paper sheet feed cassette to an image forming section through a paper sheet carrying route (hereinafter simply called an ADU), and an image is formed on one surface. The paper sheet on which an image has been formed is then stacked and contained in an intermediate tray. Subsequently, the paper sheet stacked and contained in the intermediate tray is fed again to the image forming section, and an image is then formed on its back surface. Thus, images are formed on both surfaces of a paper sheet which is then fed out onto a sheet discharge tray.
Meanwhile, electrostatic charges have been applied to paper sheets stacked on the intermediate tray, for example, through a transfer process at the image forming section. Therefore, paper sheets easily tend to be fed stuck together when they are fed again from the intermediate tray.
In addition, since a paper sheet having a surface on which an image has been formed must once be stacked and contained in the intermediate tray, an image cannot be formed sequentially on its back surface. Time loss is therefore caused so that the image forming efficiency is lowered.
To solve the above-described problems that layered paper sheets are fed and the image forming efficiency is lowered, a development has been made in an electrophotographic copying machine which adopts so-called non-stack ADU.
That is, this kind of electrophotographic copying machine carries out continuous image formation on surfaces of a plurality of sheets, excluding the intermediate tray from the ADU. Then, these paper sheets are directly sent to the image forming section, reversed by reverse carrying means, and an image is formed on the back surface of the paper sheet.
In some cases, the non-stack ADU is used with an accounting device such as a coin controller attached thereto. If data of total 4 pages are double-side-printed on two paper sheets in an electrophotographic copying machine attached with the accounting device, for example, there may be a case that inserted money runs short at the time point when printing on pages 1, 2, and 4 pages.
In this case, the paper sheet on which the third page should be printed should be discharged without carrying out printing or should be kept in the ADU in the apparatus.
However, the non-stack ADU includes a curved corner part. If a paper sheet is kept at this corner part, the paper sheet is curled into the shape of the corner part.
The appearance of the paper sheet is deteriorated and a transfer failure may occur. In addition, paper sheets cannot be discharged, with their order arranged properly, and there may be a drawback that paper sheets jam while conveying them.